How we choose to dress is inevitably connected to how we choose to identify ourselves. But what do people wear when their identity is outlawed? That question is front and center in On Swift Horses, an intimate and tender drama about two people discovering themselves on the fringes of 1950s America. Adapted from the 2019 Shannon Pufahl novel of the same name, Daisy Edgar-Jones and Jacob Elordi star as Muriel and Julius, a sister and brother-in-law who find themselves on parallel journeys of sexual exploration while living on opposite sides of the California-Nevada border. While they harbor their secrets from Julius’s brother, Lee (Will Poulter), their spiritual evolution coincides with a stylistic one.

To get the job done, director Daniel Minahan tapped Emmy-nominated costume designer Jeriana San Juan. A true master of dressing when it comes to period dramas, San Juan has delivered some of her most renowned work in projects like Netflix’s Halston, Baz Luhrmann’s The Get Down, and HBO’s The Plot Against America.

“It is never a matter of me impressing the character on the performer,” San Juan says. “It is: How is this performer going to express this character? My work is to support the performance, so the more that we can synergize, the better for everyone.”

Ahead of the movie’s April 25 release date, San Juan chatted with Harper’s Bazaar about the secrets that bubble up in her fitting room, the history of queer fashion in America, and the unexpected accessory she gave to Jacob Elordi. Read the full interview below.

jeriana san juan
Emilio Madrid

For this movie’s specific time period, where did you start with your research?

My first conversations with Dan Minahan, our director, were about how to approach the period because of the nature of our story. It all takes place in kind of an undocumented world, and the script spoke to a look for the film and a feeling for the film that weren’t going to be too heavy-handed in terms of the fashion of it all, which is easy to go down that road in the 1950s, because the clothes can feel so pinup or paper doll. We really wanted the clothes not to be an obstacle in terms of connecting to the characters and having them feel visceral and relevant and real and young.

To capture that, I really went to a lot of photo generalist research. I went to photographers like Nina Leen, Ruth Orkin, Vivian Maier. These were all female photographers of the time who were doing photojournalistic work, capturing life on the fringes. Then, I went to early feminist texts and early LGBT text for what organizations existed, including the Daughters of Bilitis, which is a deep cut for our gay and lesbian history. Daughters of Bilitis were like an early lesbian civil-rights group that formed in the mid 1950s, and they started a first-of-its-kind periodical that was in some ways a sort of Green Book, which is sort of an underground resource for people in the LGBTQIA+ community to know better where the safe spaces were, what were the clubs that you could go to, where could you meet up—that kind of thing. There are some recorded photographs, which were a lot of home photographs. It was a real kind of investigative research into the period, because it’s not necessarily what was on the runways of the time. It’s not necessarily what was highly documented. Because of the nature of the characters, who are forward thinkers, I did go to some forward-thinking artists and writers of the time. Jack Kerouac was a huge inspiration for Julius’s wardrobe.

person holding a hat in a retrothemed venue
Sony Pictures

Since queer communities in the ’50s couldn’t live their lives in an overtly public way, how did the hidden nature of that history affect your research?

It definitely made it a little more difficult. I even went to things like oral histories, just to get some more information about the concept of masc dressing at the time and what did that look like. Also, just to understand the full spectrum of the feminine ideal of the time and the masculine ideal of the time, because that was an idea that is very much played with in queer culture in general. How were we going to approach that in a way that also felt authentic and real? The greatest joy in this project was that in my fittings with Daisy and with Jacob and all of our characters—but I would say maybe Jacob and Daisy particularly—I was in on a secret with them in how they were in inhabiting their characters. They do move through the world using clothing in a unique way to both camouflage themselves at moments and then, in other moments, allow themselves to peacock a little bit more and be seen.

The first time we see Muriel at the racetrack, she’s wearing this all-white outfit. She’s almost trying to go incognito with her sunglasses and her headscarf. The next time we see her at the racetrack, she’s wearing all black. She’s not hiding her face as much. It conveys a certain degree of confidence that she’s gained since the last time she was there. What were you trying to convey about her stylistic evolution in those two looks?

Well, the first look she wears is this little trench coat and her scarf, and she’s wearing the scarf wrapped around her head because she is trying to stay clandestine and a little bit more camouflaged so that the patrons of the restaurant don’t recognize her. She’s come straight out of work, so she’s wearing her waitress uniform underneath that jacket and just kind of buttoned it up and done her best to fly under the radar. The second time she’s come back to the racetrack, she has worn this new dress. The idea of the black was in some ways to really be the polar-opposite image of the prior way we’ve seen her. It’s kind of a bold move, but it also is in some ways a safe move. We looked at so many different options for what these dresses would be, and ultimately black kind of felt like there was a strength in it and a power in it. It kind of creates a negative space in the image in an interesting way so that she does kind of fall back in a sea of women in pastel and floral or jewel-colored dresses.

daisy edgar jones as muriel
Sony Pictures

Another pivotal outfit we see on Muriel is the blue dress she wears to the queer bar in San Diego. How did that look come together?

I wanted there to feel like a definite evolution for the character. With the black dress, she’s wearing a little pair of T-strap flats, so that’s still kind of very conservative and pared down. Then, when she goes into the next look after that, it really had to feel like another layer of audacity in her evolution. I definitely wanted to move toward a color and still keep it sort of spare and not too kind of fussy and overly decorated because it just didn’t speak to Muriel’s tastes. The color ultimately came from looking at the color of periwinkle. The color of periwinkle is so closely identified with lesbian and gay culture, so that’s really where it stemmed from. Once we came up with this periwinkle blue and found this shade that looked so beautiful on her coloring, it was just about finding the right silhouette that felt almost Hitchcockian in its simplicity and boldness.

We tried a lot of different things, and Daisy is just such a magnificent performer. In the fitting when we’re trying on things, it’s wild how it happens. It’s like this magic moment when she put on that dress or what was a mockup of that dress, and it just sang. It sang. There’s no other word for it. It just felt right. We just all knew it was right. I loved how it looked, even when she was holding her shoes, walking shoeless down the subdivision. It hit all the notes that it needed to hit.

a woman in a vintage blue dress walks down a street with classic cars and historic buildings
Sony Pictures

I also love that she wears it when she knocks on Sandra’s door while Sandra is hosting the party for fellow queer women. The guests at that party are dressed much differently from how Muriel is dressed, but I also think it shows a certain fluidity of sexuality and gender—that someone doesn’t necessarily need to dress or look a certain way in order to be authentically who they are.

And I loved the idea of that kind of icy periwinkle blue walking through a sea of rich, warm, and dark colors. When she arrives there, it just feels like she is this ostrich in the room, that she would feel like an outsider and look like an outsider. That scene in particular was a real absolute joy to work on—and just the gathering of that cool, interesting queer crowd of their time. When I got into that research, I looked a lot toward the French New Wave and the beatnik scene. It’s an interesting world because they are repurposing clothes that are designed to be very wasp-waisted and hourglass and feminine and wearing them in interesting new ways. So it’s a really cool time for fashion, actually.

I love the idea of color being used as a motif for these characters. So there’s blue for Muriel, and Julius is also seen throughout the film in this yellow leather jacket. Is it leather?

It’s a deerskin jacket. It’s actually the natural color of the deerskin when it’s tanned.

I’d love to know more about what that jacket means for Julius.

So, that jacket I found at a vintage shop. It’s a 1940s deerskin jacket, and it’s almost the color of a chamois cloth. That jacket is an original vintage piece, and I ultimately had to make multiples for it to service production. But the colors are interesting. There has to be a language and a vocabulary to the look of the film. But Dan really was very conscientious that he didn’t want it to feel too curated and too guided from a color perspective. He wanted a full spectrum of color. So I tried to step out of the zone of colors here and there for both of those characters so that they didn’t feel too manicured or styled. But that jacket, it was just a really fantastic find. It felt very specific and general all at the same time, which I really loved about it. It didn’t fit him perfectly, which was honestly the best part about it because it really felt like he stole it off of some bar stool somewhere in his travels. The T-shirt that he pairs it with, we made. I mean, we ultimately made almost everything for Jacob because he stands six-foot-five or six-foot-six, and typically the clothes of the period are not really suitable for that height.

jacob elordi bts
Courtesy of Jeriana San Juan
jacob elordi as julius
Courtesy of Jeriana San Juan

How involved were Daisy and Jacob in the development of their looks? How do they help form their characters physically and visually?

Again, there’s just something that starts to click in the fitting room. When Jacob puts on those trousers with the double pleat and the high waist, and the way that particular fabric falls on his body, it just kind of clicks. He starts to shift his posture and how he stands in the clothes and starts to find the way that Julius kind of stands and moves.

a convertible car with two occupants inside
Courtesy of Jeriana San Juan

I’m always so curious how the actors themselves add little visual quirks to their characters. So I love to hear that.

You know what’s an interesting story—we share little secrets about the character in the fitting room, things that we don’t even tell anybody else about. Why does Muriel have this blouse? It was handed down to her from her mother. ... Those kinds of things are things we talk about in the fitting room. But another thing I did for Julius and Henry was I had some lighters, these little silver made-out-of-tin original 1950s-style lighters, that I put in the pockets of their pants. They just felt organic and true to what the character would have. I would plant them in there, so when they put on their clothes and they start to inhabit the character, Jacob put his hands in his pockets. He’s like, “What’s this?” And I was like, “Oh, that’s Julius’s lighter, I guess.” And he used it in the shoot.

Another fun little note is what Muriel wears in the very first scene of this movie—the most complacently, idealistically, feminine, 1950s that she looks through the whole movie. She’s wearing this red, white, and blue outfit with the navy-and-white gingham, and it’s all very quintessentially American and Midwest and sweet in a lot of ways. She’s wearing a pearl necklace, which ... is like one of those things that’s like, yeah, women have passed down their mother’s pearls for generations, and what is it behind pearls? Why do they carry so much meaning? This idea of pearls being a symbol of purity and class and elegance ... Once I put the pearl necklace on, it sort of took on the look of a collar, like some form of a leash. And you’ll notice she doesn’t wear them ever again after that.

This interview has been lightly edited and condensed for clarity.